Thirty eccentric contractions (ECs) were imposed upon rat dorsiflexors (n= 46) by activating the peroneal nerve and plantarflexing the foot ≈40 deg, corresponding to a sarcomere length change over the range 2.27‐2.39 μm for the tibialis anterior and 2.52‐2.66 μm for the extensor digitorum longus. Animals were allowed to recover for one of 10 time periods ranging from 0.5 to 240 h, at which time muscle contractile properties, immunohistochemical labelling and gene expression were measured. Peak isometric torque dropped significantly by ≈40 % from an initial level of 0.0530 ± 0.0009 Nm to 0.0298 ± 0.0008 Nm (P < 0.0001) immediately after EC, and then recovered in a linear fashion to control levels 168 h later. Immunohistochemical labelling of cellular proteins revealed a generally asynchronous sequence of events at the cellular level, with the earliest event measured being loss of immunostaining for the intermediate filament protein, desmin. Soon after the first signs of desmin loss, infiltration of inflammatory cells occurred, followed by a transient increase in membrane permeability, manifested as inclusion of plasma fibronectin. The quantitative polymerase chain reaction (QPCR) was used to measure transcript levels of desmin, vimentin, embryonic myosin heavy chain (MHC), myostatin, myoD and myogenin. Compared to control levels, myostatin transcripts were significantly elevated after only 0.5 h, myogenic regulatory factors significantly elevated after 3 h and desmin transcripts were significantly increased 12 h after EC. None of the measured parameters provide a mechanistic explanation for muscle force loss after EC. Future studies are required to investigate whether there is a causal relationship among desmin loss, increased cellular permeability, upregulation of the myoD and desmin genes, and, ultimately, an increase in the desmin content per sarcomere of the muscle.
Previous research using hypothetical case scenarios has suggested a model of decision making in discharge planning involving at least two steps. The first is to assess the availability of a caregiver, and the second is to examine the complexity of the patient's situation regarding follow-up care needs, physical functioning, and compliance. The combination of these factors then influences the choice of discharge option. The present study attempted to validate and extend the model using actual cases in a retrospective chart review. The four variables of the original model correctly classified 68% of patients by discharge type and accounted for 29% of the variance. An expanded model that included chore assistance, living situation, caregiver availability, medical need, and patient age was able to account for an additional 19% of the variance in the discharge plan.
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